THE chief executive-designate of embattled telecoms firm Marconi, John Mayo, has resigned.

The resignation comes amid a collapse of Marconi shares after it warned sales would be 15% lower this year and operating profits may be halved.

The firm also announced 1,500 job losses in the UK, including 500 in Poole, Dorset, and an as yet unspecified number in Coventry.

The shares nose-dived 54% on Thursday after the announcement, and there was no reprieve yesterday - by the close of trading, Marconi shares were down 7% or 8p at 104.5p.

Mr Mayo, deputy chief executive of the company, had been due to succeed current chief executive Lord Simpson, who would have become chairman.

A spokesman for the company later said Lord Simpson would stay in his current position, as would chairman Sir Roger Hurn.

Marconi said the economic slowdown meant customers were delaying purchases as they tighten their belts - just two months after it said it believed it would achieve growth this year.

Last year, its shares hit a high of #12.50 but have been falling ever since on the back of the gloom surrounding the tech and telecom sector.

Last month, shares hit record lows of 237p, which today's close of 104.5p easily surpassed.

Its closing price gives Marconi a market value of #2.91 billion, placing it firmly at the bottom of the Footsie.

Following his resignation, Mr Mayo said: "Marconi is a great company going through difficult times that are not of its own making. The entire workforce faces immediate short term challenges and it is inevitable that sacrifices will have to be made.

"I wish all my colleagues good fortune and look forward to my Marconi shares under George's (Lord Simpson's) stewardship appreciating in value over the coming years."

Lord Simpson said: "The speed and severity of the downturn in the markets clearly requires firm action and the solutions will not emerge overnight.

"However, the longer-term prospects of the industry remain good, we are soundly financed and we believe we are much better positioned than a number of our competitors."

"We hope that this act by Mr Mayo to take full responsibility for the company's plight and fall from grace will restore shareholders' confidence in the company," he said.

"John Mayo has been responsible for putting all the company's eggs in the telecoms basket and therefore his going will mean that the company will be able to look back to where they were successful in the past."

But he added: "This will come as no comfort to the people who will lose their jobs as a consequence of the plant closure in Poole."